Ventilators for basements and crawlspaces are known in the art, including ventilators that are held in place by spring clips. See, for example, Sarazen (U.S. Pat. No. 4,669,371). However, such ventilating units do not eliminate the problem of mold and other organic growth in the crawlspace, and in fact can exacerbate the problem by allowing access of such organic material into the crawlspace.
Rain, humidity, mold, and pollen often find their way into existing ventilators, and thence into the basement or crawlspace. If one of the existing ventilators were to be equipped with a filter, the filter would be subject to moisture, making it soggy, and in fact creating a potential breeding place for mold, and the filter would not be easily replaced, and may require professional replacement using tools of the trade.
Moisture gets into crawlspaces many other ways than through ventilators. For example, ground water typically evaporates into a crawlspace, as much as ten gallons daily for every 700 square feet of dirt. Additionally, brick and concrete foundation walls commonly absorb and transmit outside moisture to the interior space.
Mold spores and pollen thrive in a moist crawlspace environment, and consequently indoor air quality within a home or building is negatively affected. Moreover, mold and moisture cause structural damage, especially to wood structures that can warp, weaken, and rot when exposed to mold and moisture.
The existing ventilators simply do not address these problems in a coordinate fashion. When the existing ventilators only address one or two of these problems, then typically the other problems are only made worse.